Drying of Hierarchically Organized Porous Silica Monoliths–Comparison of Evaporative and Supercritical Drying

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Authors

  • Richard Kohns
  • Jorge Torres-Rodríguez
  • Daniel Euchler
  • Gudrun Reichenauer
  • Dirk Enke
  • Nicola Huesing

Organisational units

External Organisational units

  • SMBS - University of Salzburg Business School, Sigmund-Haffner-Gasse 18, A-5020 Salzburg, Austria
  • Salzburg Center for Smart Materials
  • Bavarian Center for Applied Energy Research, Wuerzburg, Germany
  • Leipzig University

Abstract

In this study, we present a detailed comparison between a conventional supercritical drying process and an evaporative drying technique for hierarchically organized porous silica gel monoliths. These gels are based on a model system synthesized by the aqueous sol–gel processing of an ethylene-glycol-modified silane, resulting in a cellular, macroporous, strut-based network comprising anisotropic, periodically arranged mesopores formed by microporous amorphous silica. The effect of the two drying procedures on the pore properties (specific surface area, pore volume, and pore widths) and on the shrinkage of the monolith is evaluated through a comprehensive characterization by using nitrogen physisorption, electron microscopy, and small-angle X-ray scattering. It can clearly be demonstrated that for the hierarchically organized porous solids, the evaporative drying procedure can compete without the need for surface modification with the commonly applied supercritical drying in terms of the material and textural properties, such as specific surface area and pore volume. The thus obtained materials deliver a high specific surface area and exhibit overall comparable or even improved pore characteristics to monoliths prepared by supercritical drying. Additionally, the pore properties can be tailored to some extent by adjusting the drying conditions, such as temperature.

Details

Original languageEnglish
Article number71
JournalGels : open access physical and chemical gels journal
Volume9.2023
Issue number1
DOIs
Publication statusPublished - 16 Jan 2023